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add comments and update test cases.

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keenwolf 2021-02-02 23:35:45 +08:00
parent f21e22ae2c
commit 9beb7689cc
5 changed files with 235 additions and 1220 deletions
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18
base/common/DateLUTImpl.h
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@ -274,23 +274,31 @@ public:
return res / 3600;
}
/** Calculating offset from UTC in seconds.
* which means Using the same literal time of "t" to get the corresponding timestamp in UTC,
* then subtract the former from the latter to get the offset result.
* The boundaries when meets DST(daylight saving time) change should be handled very carefully.
*/
inline time_t timezoneOffset(time_t t) const
{
DayNum index = findIndex(t);
/// Calculate daylight saving offset first, ignore the leap seconds
/// Calculate daylight saving offset first.
/// Because the "amount_of_offset_change" in LUT entry only exists in the change day, it's costly to scan it from the very begin.
/// but we can figure out all the accumulated offsets from 1970-01-01 to that day just by get the whole difference between lut[].date,
/// and then, we can directly subtract multiple 86400s to get the real DST offsets for the leap seconds is not considered now.
time_t res = (lut[index].date - lut[0].date) % 86400;
/// As so far to know, the maximal DST offset couldn't be more than 2 hours, so after the modulo operation the remainder
/// will sits between [-offset --> 0 --> offset] which respectively corresponds to moving clock forward or backward.
res = res > 43200 ? (86400 - res) : (0 - res);
/// Check if has a offset change during this day
/// Check if has a offset change during this day. Add the change when cross the line
if (lut[index].amount_of_offset_change != 0 && t >= lut[index].date + lut[index].time_at_offset_change)
res += lut[index].amount_of_offset_change;
return res + offset_at_start_of_epoch;
}
/** Only for time zones with/when offset from UTC is multiple of five minutes.
* This is true for all time zones: right now, all time zones have an offset that is multiple of 15 minutes.
*

6
src/Functions/DateTimeTransforms.h
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@ -407,7 +407,7 @@ struct ToHourImpl
using FactorTransform = ToDateImpl;
};
struct timezoneOffsetImpl
struct TimezoneOffsetImpl
{
static constexpr auto name = "timezoneOffset";
@ -420,8 +420,8 @@ struct timezoneOffsetImpl
{
return dateIsNotSupported(name);
}
/////need to do
using FactorTransform = ToDateImpl;
using FactorTransform = ToTimeImpl;
};
struct ToMinuteImpl

2
src/Functions/timezoneOffset.cpp
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@ -7,7 +7,7 @@
namespace DB
{
using FunctiontimezoneOffset = FunctionDateOrDateTimeToSomething<DataTypeInt32, timezoneOffsetImpl>;
using FunctiontimezoneOffset = FunctionDateOrDateTimeToSomething<DataTypeInt32, TimezoneOffsetImpl>;
void registerFunctiontimezoneOffset(FunctionFactory & factory)
{

1381
tests/queries/0_stateless/01699_timezoneOffset.reference
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File diff suppressed because it is too large Load Diff

48
tests/queries/0_stateless/01699_timezoneOffset.sql Normal file → Executable file
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@ -1,20 +1,46 @@
/* timestamp == (Europe/Moscow) */
/* Test the DST(daylight saving time) offset changing boundary*/
SELECT 'DST boundary test for Europe/Moscow:';
SELECT number,(toDateTime('1981-04-01 22:40:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(4);
SELECT number,(toDateTime('1981-09-30 23:00:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(18);
SELECT 'DST boundary test for Asia/Tehran:';
SELECT number,(toDateTime('2020-03-21 22:40:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(4);
SELECT number,(toDateTime('2020-09-20 23:00:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(18);
SELECT number,(toDateTime('1981-04-01 00:00:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
SELECT number,(toDateTime('1981-09-30 00:00:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
SELECT number,(toDateTime('2020-03-21 00:00:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
SELECT number,(toDateTime('2020-09-20 00:00:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
SELECT 'DST boundary test for Australia/Lord_Howe. This is a special timezone with DST offset is 30mins with the timezone epoc also lays at half hour';
SELECT timezoneOffset(toDateTime('2018-08-21 22:20:00', 'Australia/Lord_Howe'));
SELECT timezoneOffset(toDateTime('2018-02-21 22:20:00', 'Australia/Lord_Howe'));
SELECT 'DST boundary test for Australia/Lord_Howe:';
SELECT number,(toDateTime('2020-10-04 01:40:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(4);
SELECT number,(toDateTime('2019-04-07 01:00:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(18);
SELECT number,(toDateTime('2020-10-03 00:00:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
SELECT number,(toDateTime('2019-04-06 00:00:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS k, timezoneOffset(k) AS t, toUnixTimestamp(k) as s FROM numbers(200);
/* The Batch Part. Test period is whole 4 days*/
SELECT '4 days test in batch comparing with manually computation result for Europe/Moscow:';
SELECT toUnixTimestamp(x) as tt, (toDateTime('1981-04-01 00:00:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(576) where res != calc;
SELECT toUnixTimestamp(x) as tt, (toDateTime('1981-09-30 00:00:00', 'Europe/Moscow') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(576) where res != calc;
SELECT '4 days test in batch comparing with manually computation result for Asia/Tehran:';
SELECT toUnixTimestamp(x) as tt, (toDateTime('2020-03-21 00:00:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(576) where res != calc;
SELECT toUnixTimestamp(x) as tt, (toDateTime('2020-09-20 00:00:00', 'Asia/Tehran') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(576) where res != calc;
/* During this test we got unexpected result comes from the toDateTime() function when process the special time zone of 'Australia/Lord_Howe', which may be some kind of bugs. */
SELECT 'The result maybe wrong for toDateTime processing Australia/Lord_Howe';
SELECT toUnixTimestamp(x) as tt, (toDateTime('2020-10-04 01:40:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(18) where res != calc;
SELECT toUnixTimestamp(x) as tt, (toDateTime('2019-04-07 01:00:00', 'Australia/Lord_Howe') + INTERVAL number * 600 SECOND) AS x, timezoneOffset(x) as res,(toDateTime(toString(x), 'UTC') - x ) AS calc FROM numbers(18) where res != calc;
/* Find all the years had followed DST during given period*/
SELECT 'Moscow DST Years:';
SELECT number, (toDateTime('1970-06-01 00:00:00', 'Europe/Moscow') + INTERVAL number YEAR) AS DST_Y, timezoneOffset(DST_Y) AS t FROM numbers(51) where t != 10800;
SELECT 'Moscow DST Years with perment DST from 2011-2014:';
SELECT min((toDateTime('2011-01-01 00:00:00', 'Europe/Moscow') + INTERVAL number DAY) as day) as start, max(day) as end, count(1), concat(toString(toYear(day)),'_',toString(timezoneOffset(day)))as DST from numbers(365*4+1) group by DST order by start;
SELECT 'Tehran DST Years:';
SELECT number, (toDateTime('1970-06-01 00:00:00', 'Asia/Tehran') + INTERVAL number YEAR) AS DST_Y, timezoneOffset(DST_Y) AS t FROM numbers(51) where t != 12600;
SELECT 'Shanghai DST Years:';
SELECT number, (toDateTime('1970-08-01 00:00:00', 'Asia/Shanghai') + INTERVAL number YEAR) AS DST_Y, timezoneOffset(DST_Y) AS t FROM numbers(51) where t != 28800;